1. Field of the Invention
This invention is generally directed to daytime running light systems for surface transportation vehicles which include control circuitry for activating the vehicle headlights under normal daylight conditions upon sensing of the vehicle ignition and starter. More particularly, the present invention is directed to an automated ambient condition response daytime running light system which includes a daytime running light control circuit for activating the highbeam filaments at low energy levels whenever the starter motor is OFF and the ignition is ON which daytime running light control circuit is automatically overridden and de-activated by a navigational lighting control circuit which is responsive to ambient condition sensors and which is operable to activate the vehicle headlights, taillights and other exterior running like at normal power levels when conditions such as low light levels, fog or moisture have been sensed or whenever the vehicle windshield wiper motor has been activated. In one embodiment, the daytime running light control circuit also simultaneously activates the parking lights so as to illuminate the vehicle tail lights. The system further provides an automatic override of the daytime running light and navigational lighting control circuits by manual activation of the vehicle headlight switch, by external override or by parking brake engagement.
2. History of the Related Art
Studies have shown that accident rates can be reduced among surface transportation vehicles such as automobiles, trucks, buses and the like merely be making such vehicles more conspicuous. There are numerous proposals for utilizing existing navigational light devices of vehicles including headlights, taillights, ICC trailer lights and the like for improving the manner in which the vehicle is made conspicuous in the daytime. Some proposals energize the highbeam filaments of the vehicle headlamp assemblies at reduce power and others energize the lowbeam filaments of the headlamp assemblies at normal power. In addition to the foregoing, some versions of both highbeam and lowbeam designs also energize existing taillight and/or parking light assemblies. Currently, some state and national government agencies are considering, or have adopted, legislation describing or requiring the use of such devices to provide an added safety factor to vehicle operation. It appears that the general trend is to require daytime running light systems on all automotive vehicles including newly manufactured trucks, buses, and cars. Such regulations, however, may also be extended to require the retrofitting of vehicles which are currently in service.
In the U.S. Pat. No. 4,684,819 to Haag et al., a headlight control system is disclosed wherein headlights are energized at reduced intensity in response to predetermined vehicle operating conditions. In U.S. Pat. No. 4,899,832 to Kataoka, a headlamp control circuit is disclosed which provides a by-pass for the manual lighting switch. In this patent, the headlamps are automatically turned on when the engine operation becomes stable after a completion of engine start-up. U.S. Pat. No. 4,686,423 to Eydt discloses an automatic headlight control circuit for operating the headlights of an automotive vehicle when the engine is operating and wherein the headlights are energized at a reduced power level. Additional examples of prior art daytime running light systems are disclosed in U.S. Pat. Nos. 4,831,310 to Heintzberger et al. and 4,667,129 to Papil et al.
In addition to improvements in developing daytime running light systems, there have also been numerous proposals for automatically controlling vehicle lighting systems to activate at normal power intensity levels during appropriate ambient conditions such as at low light levels, darkness, and where weather interferes with normal sight distance, such as in periods of rain or fog. Such systems incorporate detection devices which activate the vehicle lighting system in response to darkness or to the detection of moisture. Some of these systems further provide for sensing the activation of windshield/wiper controls or motors so as to automatically activate the vehicle lighting system when the wiper system is activated.
As with daytime running lights, many state governmental agencies have adopted legislation which requires that whenever the vehicle windshield wipers are engaged, that the vehicle lowbeams and taillights must also be illuminated. As with the daylight running light system, it is the desire of governmental agencies, as well as insurance companies, to make vehicles more conspicuous during periods of poor ambient visibility conditions.
Some examples of controlling the navigational lighting systems of surface vehicles during periods of poor ambient light and visibility conditions are disclosed in U.S. Pat. Nos. 4,956,562, 5,136,209, and 5,185,558 all assigned to the Assignee of the present application.
Both the daytime running light systems and the ambient condition navigational lighting control systems of the prior art provide for increased safety in surface transport vehicle operation. However, there are certain problems inherent in some systems which can lead to unsafe conditions. For instance, in some current systems which are being utilized in surface transportation vehicles, power is supplied whenever the motor of the vehicle is engaged to activate the headlight system. In order to conserve on energy and to prolong the life of the headlights, many such systems reduce the power which is supplied to the highbeam filament of the headlight system. With such systems, normally no power is supplied to the vehicle taillights. In the event the ambient conditions change during operation of the vehicle, such as at dusk or during periods of rain when visibility makes the vehicle less conspicuous, the vehicle operator may realize that the headlights are illuminated although at reduced power. If the vehicle operator does not take action to manually disengage the daytime running lighting system by manually engaging the lowbeams or the highbeams of the vehicle system by operation of the vehicle headlight switch, the taillights of the vehicle will not be illuminated, thus creating a situation where the vehicle is not conspicuous from the rear during such periods of poor ambient conditions. Therefore, in one sense, the daytime running system provides a false sense of safety and security to the vehicle operator.